Search

Cadmium is one of the most important environmental contaminants. Animals grazing on natural pastures are particularly exposed to cadmium. Sheep are mostly reared in extensive and grazing systems. Therefore, sheep may accumulate larger amounts of cadmium compared to other ruminant species and are a good indicator of exposure to cadmium contamination in a given area. The determination of cadmium concentrations in the muscles, livers and kidneys of lambs and sheep was carried out in the Czech Republic during the period 2001--2022. The average cadmium content in the livers and kidneys of all the lambs was 0.037 ± 0.006 and 0.061 ± 0.013 mg.kg-1, respectively. The average cadmium content in the livers and kidneys of all the sheep was 0.319 ± 0.047 and 1.255 ± 0.204 mg.kg-1, respectively. The maximum limit for human consumption was not exceeded in any of the 24 samples in the lambs but was exceeded in 5 of 33 liver samples and 12 of 33 kidney samples in the adult sheep. The average value of cadmium in the muscles of the lambs and sheep was 0.004 ± 0.001 mg.kg-1. The maximum limit for human consumption was not exceeded in any muscle sample. The cadmium content in both the liver and in the kidney differs significantly between the lambs and sheep, being higher in the sheep (P < 0.001 for both comparisons). No statistically significant trend of a decrease in the cadmium content in the lamb and sheep tissues was found during the observed time (P > 0.05). We can sum up that there is an evident need for further monitoring of the cadmium concentration in lamb and sheep tissues in the Czech Republic. [ABSTRACT FROM AUTHOR]

Abstract Mercury is one of the important pollutants of the environment. Therefore, it’s necessary to monitor quantity of mercury especially in aquatic ecosystems. The main goal of the presented study was to compare the content of total mercury in tissues of fish coming from the Czech Republic, an important carp exporter, with focus on comparison of mercury content between 3 different ponds, its comparison between different fish species and between different tissues of the same species, and estimation whether the mercury content in tissues meets the limit given in the Commission Regulation (EC) No. 1881/2006 or not. Total mercury concentration was measured in 90 fish specimen sampled from three ponds (Velky Kocelovicky, Mysliv and Zehunsky) in autumn 2018. The values of total mercury in fish tissues was measured by atomic absorption spectrometry. The content of total mercury in the tissues decreased as follows: muscle > liver > gonads > scales. The highest average content of total mercury in muscle was 0.1517 ± 0.0176 mg/kg coming from pike caught in Velky Kocelovicky pond. In contrast, the lowest average content of total mercury in muscle 0.0036 ± 0.0003 mg/kg was found in carp tissue coming from the locality of Zehunsky pond. We confirmed that the predatory fish are more exposed to mercury than non-predatory fish. None of the monitored localities exceeded the set regulatory limit. Thus, our study shows that fish coming from these ponds are safe in terms of total mercury content.

Mutual interactions of the phytohormones, cytokinins and auxin determine root or shoot identity during postembryonic de novo organogenesis in plants. However, our understanding of the role of hormonal metabolism and perception during early stages of cell fate reprogramming is still elusive. Here we show that auxin activates root formation, whereas cytokinins mediate early loss of the root identity, primordia disorganisation and initiation of shoot development. Exogenous and endogenous cytokinins influence the initiation of newly formed organs, as well as the pace of organ development. The process of de novo shoot apical meristem establishment is accompanied by accumulation of endogenous cytokinins, differential regulation of genes for individual cytokinin receptors, strong activation of AHK4-mediated signalling and induction of the shoot-specific homeodomain regulator WUSCHEL. The last is associated with upregulation of isopentenyladenine-type cytokinins, revealing higher shoot-forming potential when compared with trans-zeatin. Moreover, AHK4-controlled cytokinin signalling negatively regulates the root stem cell organiser WUSCHEL RELATED HOMEOBOX 5 in the root quiescent centre. We propose an important role for endogenous cytokinin biosynthesis and AHK4-mediated cytokinin signalling in the control of de novo-induced organ identity. [ABSTRACT FROM AUTHOR]

Objectives: The study was designed to assess the pollution of the Svitava and Svratka rivers in and around the industrial city of Brno (Czech Republic) by persistent organic pollutants using selected biochemical markers in chub., Design: Levels of selected biochemical markers were measured in liver and plasma samples of chub. The concentrations of persistent organic pollutants (POPs) were determined in bottom sediment, semi-permeable membrane devices (SPMDs) and muscle samples, and consequently used for correlation with biochemical markers., Results: Significant alterations (p < 0.05) in some biochemical markers were observed and associated with combined exposure to pollutants. The highest levels of pollutants were found at sites situated downstream from Brno. The most widespread changes were identified in the function of phase I detoxifying enzymes. Significant positive correlations were observed in cytochrome P450 content and DDT concentration in the semi-permeable membrane device (p = 0.019, rs = 0.886), and between ethoxyresorufin-O-deethylase activity and content of DDT (p = 0.041, rs = 0.352) and polychlorinated biphenyls (p = 0.034, rs = 0.365) in muscle tissues of indicator fish., Conclusion: The results presented in our study indicate the highest contamination of sites situated downstream from Brno, where the intensive industrial and agricultural activities as well as domestic waste and sewage most probably comprise the main impact sources of the enhanced level of pollutants and some biochemical markers in fish.

Objectives: The aim of this study was to assess the effect of metals, with special attention of cadmium (Cd), content of the Svitava and Svratka rivers (Czech Republic) on levels of thiol compounds such as metallothioneins (MT), glutathione (GSH/GSSG), and cysteine (Cys) concentrations in chub (Leuciscus cephalus L.) liver and their use as biomarkers., Design: Levels of thiol compounds in fish liver were determined by the differential pulse voltammetry Brdicka reaction. Cadmium content in L. cephalus liver was measured by atomic absorption spectometry (AAS) with electrothermal atomization. The contents of thiols and Cd were correlated with the Cd and metals content of river bottom sediments., Results: Results were inconsistent with those of experimental studies. Correlations between liver Cd content and MT, Cys, GSSG were not significant in any locality (p > 0.05). Cd liver content was negatively (p< 0.05) correlated with GSH at one (Zidlochovice) of the seven tested sites. GSH and GSSG correlated negatively in five localities (p > 0.05). Correlations between Cd in sediment and Cys and GSSG (p > 0.05), and MT was negative (p< 0.05). The relationship between sum of metals value and MT was negative (p< 0.05), similarly with GSSG (p > 0.05)., Conclusion: Many factors influence content of MT, GSH, and GSSG, and data for Cd were equivocal. Monitoring the aquatic ecosystem to identify metal content using thiol compounds in fish liver as biomarkers is complex. More relevant data including laboratory experiments will be required to assess most of the factors influencing thiols and their relevance to Cd contamination.

Objectives: Exposure to mercury, a risk factor for neuro-developmental toxicity, was evaluated in the Czech Republic by performing mercury determination using human hair as an indicator., Methods: Hair samples from Czechs (n=311; 2-66 years old) were analyzed for mercury content. Total mercury was analysed by mercury analyzer AMA 254., Results: The highest total mercury content found in sampled hair was 3.55 microg/g and the lowest content was 0.015 microg/g. No correlation was found between the mercury levels in the sampled hair and the subject's age, gender, and the amount of amalgam fillings. A total of 38 hair samples were analyzed for methylmercury content., Conclusion: The results show a positive correlation between the total mercury content in human hair and the consumption of marine and freshwater fish. Hair are a very good indicator of fish consumption.